1. Field of the Invention
The present invention relates generally to providing fall protection for loads in an elevated environment, and more particularly, to a method for providing fall protection for human and non-human loads while the load is supported in an elevated environment by an aerial lift and/or while transferring between elevated points on generally adjacent structures.
2. Description of the Background Art
People often work in elevated environments wherein the risk of falling or loss of support is a constant possibility. Construction and maintenance workers often operate from aerial lift systems in elevated environments on or in connection with buildings, towers, bridges, dams, as well a host of other tall man-made and natural structures. In addition, non-human cargo loads are frequently placed in, or transferred to/from elevated points. Accordingly, providing fall protection for human and non-human loads is an important consideration when operating in elevated environments and/or above-ground-level.
There particularly exists a need for providing adequate fall protection for workers operating from aerial lift systems. Aerial lift systems refer to a wide variety of systems designed to place and/or maintain a worker in an elevated environment. As used herein the “aerial lift systems” include movable lifts, scissor lifts, cranes, tree lifts, man lifts, elevator lifts, bucket trucks, airborne lifting vehicles, such as helicopters, temporary structures such as scaffolding, suspension devices, or any other device, apparatus, or system, capable of lifting, elevating, or suspending a human or non-human load in an elevated environment that is subject to a possibility, no matter how remote, of failure. Aerial lifts are often used to support workers while working on and/or transferring to an adjacent structure. Since any aerial lift is subject to failure when operating from or in connection with an aerial lift, it is critically important to provide fall protection for the load, particularly for human loads.
There are a number of basic devices, such as safety harnesses, designed to secure a load in an elevated environment. While the design of known safety devices varies, harnesses for human loads commonly consist of a pair of shoulder straps attached to a waist or chest belt. Some harnesses incorporate suspender style straps with a tether point-of-attachment on the front center of the chest/waist strap. Others comprise a Y-shaped design, where the shoulder straps are connected to a strap extending vertically from the waist belt to form a three-point intersection. Conventional harnesses are typically constructed of nylon webbing, and commonly include padding. Such harnesses are designed to support the human load (i.e., body weight) by the torso and shoulders for suspension.
Sit harnesses comprise another category of fall protection devices commonly used when a person is supported in a suspended configuration. Also known as a pelvic harness, a bosun's seat, a rescue harnesses, or a rigger's harnesses these devices typically suspend the user in a seated posture. The basic design of a sit harness includes a waist belt connected to leg loops routed around the top of the thighs. The point of the tether attachment typically extends directly in front of the upper pelvic region.
Full-body harnesses comprise a combination of sit harnesses and chest harnesses. While there are a number of variations of the basic design of the harness, full-body harnesses commonly include leg loops, shoulder straps, and either a waist belt, a chest belt, or both. The design of the full body harness is such that it assists the user in maintaining an upright, seated posture while suspended.
As note above, human and non-human loads are introduced into elevated environments in a wide variety of applications. For example, bucket trucks, helicopters, and cranes are routinely used to place human and non-human loads in elevated environmental applications.
In addition, rotary winged aircraft, such as helicopters, have been used in a wide variety of load transfer operations, including human external load (“HEL”) operations and non-human external load operations. Human external load operations typically involve the transportation of a passenger suspended by a cable assembly under the helicopter. For example, helicopters equipped with load suspension points, or hooks, are capable of transporting loads in sling configuration wherein the load is suspended beneath the helicopter by a suspension apparatus. In other applications, helicopters carry cargo as well as human loads in various configurations external to the fuselage, such as on the skids or on skid-mounted platforms. For example, load-bearing platforms may be affixed to the helicopter to permit persons to operate external to the crew compartment. In other situations, a person may stand on one of the helicopter landing skids and operate in the external environment. HEL operations are commonly performed in transmission line maintenance and repair procedures in the electrical power industry, in the logging industry to access remote work sites, and for emergency rescue operations.
The present inventor has contributed significantly to advances in helicopter external load operations, particularly external human load operations. My U.S. Pat. No. 4,673,059 discloses a method and system for placing a load, which may consist of a combination of personnel and equipment, on or in proximity to components of an energized power transmission line. My U.S. Pat. No. 5,417,304 discloses a method for suspending a load from a rotary winged aircraft, such as a helicopter, using an apparatus that incorporates an emergency release activated by the suspended person. The methods disclosed in the '059 and '304 patents concern operations involving loads suspended beneath a helicopter, and do not particularly address issues relating to fall protection for the external load.
In certain situations, it is necessary or desirable to transfer external loads from a hovering helicopter, bucket truck, crane, or other elevated configuration to a structure, such as a power transmission tower, or an energized or de-energized power transmission line, ground wire, or other elevated point or structure. With regard to helicopters and other lift vehicles, the methods disclosed in the '059 and '034 patents do not disclose suitable apparatus or methods for accomplishing the transfer of an external load from the vehicle, such as a hovering helicopter, to an elevated structure while maintaining adequate safeguards for both the vehicle as well as the load. While the '304 patent discloses an emergency release, the system disclosed therein is a release-on-command type system that requires the suspended person to: (1) realize the existence of an emergency with the helicopter; and (2) manually activate the quick release to permit the helicopter to pull away. As should be apparent, the primary concerns in such human transfer applications involve maintaining adequate fall protection for the person during the transfer procedure without limiting helicopter operations, particularly the availability of emergency maneuvers and operations. It is critical to maintain full fall protection for the person through the entire transfer process, while, at the same not limiting the operation of the helicopter in emergency situations.
Currently, there is little standardization and a general lack of safety procedures practiced by those performing HEL operations. While regulations exist regarding the physical and structural characteristics of external load operations, little consideration has been given to the issue of humans as external loads. Federal Aviation Regulations applicable to rotorcraft operations, particularly those referring to human external loads, are found in Title 14 of the Code of Federal Regulations (CFR). The collection of FAA regulations found in 14 CFR is often referred to as the Federal Aviation Regulations (FARs). Within 14 CFR, part 133 pertains directly to rotorcraft external load operations and contains subparts that address applicability, certification rules, operating rules, and related requirements. In addition, part 27 requires that any external load attaching means must include a quick-release system to enable the pilot to release the external load quickly during flight. While the regulations address a number of areas, they provide no specific detail regarding the attachment method, human load transfer methods, or the structure or function of quick-release devices.
One common, yet inherently risky prior art method of transferring an external human load from a hovering helicopter to a structure, in a non-sling configuration, consists of bringing the helicopter to a hover immediately adjacent to a structure, wherein the helicopter may be stabilized by the placement of one or both skids (or wheels) on the structure, thereby allowing the person to step from the helicopter to the structure. This method, however, is significantly flawed in that, to avoid tethering the helicopter to the structure and thereby limiting the availability of emergency flight procedures (e.g. emergency pull-away), there exist periods of time during the transfer that the person is without fall protection, and consequently at substantial risk.
As a result of the lack of adequate safety methods there have been a number of rotorcraft accidents in connection with HEL operations. During the period from 1973 through 1995, it has been reported that there were 473 external load operations in which the helicopters were involved in either an accident or an incident. Of the 473 accidents listed, a substantial number involved operations using a sling line or sling load. Accordingly, it is recognized that the predominant cause of external load accidents involves problems with the sling line/load.
Thus, although HEL operations have been practiced, there remains a need for safer methods for transferring external loads from hovering helicopters. More particularly there exists a need for an improved method of safely transferring a load from a hovering helicopter to a structure, such as a power transmission tower or line or any other elevated structure, while simultaneously providing total fall protection for the human and preserving emergency operating procedures for the helicopter and crew by incorporating an emergency quick release. Since loads are also transferred using other vehicles, such as aerial lift vehicles including bucket trucks and cranes, there exists a substantially similar need for an improved method for providing fall protection for human and non-human loads in elevated environments and during transfer in elevated environments.